Objectives:
The objectives of this experiment are:
The objectives of this experiment are:
1.
To study and evaluate the effects of different formulation of
ointment on the physical characteristics of the formed ointment.
2.
To study the theory of drug release rate for different formulation
of ointment.
Introduction:
Ointment
is aa topical medication applied on the body surfaces. In medical terms, an
ointment is defines as a homogeneous, viscous, semi-solid preparation with a
high viscosity, that is used for external application. An ointment has
medicated ingredients which serve a protective, therapeutic, or prophylactic
purpose when applied on the skin or mucous membranes .The medicated stuff or
the ingredients present inside the ointment is actually the main base of
ointments. There are 4 main ointment bases:
o Hydrocarbon bases, e.g. hard paraffin,
soft paraffin, microcrystalline wax and ceresine
o Absorption bases like as wool fat, beeswax
o Water soluble bases like as macrogols 200,
300, 400
o Emulsifying bases like as emulsifying wax
Ointment is used to relieve the symptoms of dry
skin conditions, such as cracked, scaly and itchy skin. The emulsifying
ointment leaves a thin layer of oil on the skin's surface that stops water
evaporating. This results in a soothing, softening and moisturising effect. In
general this drug is used to moisturise and soften dry skin. They are
used as emollients or for the application of active ingredients to the skin for
protective, therapeutic, or prophylactic purposes and where a degree of
occlusion is desired.
The desirable qualities in ointment included smooth, never gritty. The
choice of an ointment base is of the utmost importance, and although it may be
impossible for any single base to be ideal in every respect and should not
cause sensitization or irritation, either to unabraded or traumatized skin.It
also should not dehydrate the area to which it is applied,should be inert and
compatible with a wide range of medicinal substances and with other bases with
which it is likely to be mixed.
More trituration is necessary in preparing powders for incorporation into
ointments than powders to be used in tablets or capsules. Methods of preparation
of ointments included trituration and fusion. In trituration, finely subdivided
insoluble medicaments are evenly distributed by grinding with a small amount of
the base followed by dilution with gradually increasing amounts of the base,
while in fusion, the ingredients are melted together in descending order of
their melting points and stirred to ensure homogeneity.
Apparatus:
The apparatus required were a measuring cylinder, a weighing boat, a 100ml beaker, heater, a set of slap
& spatula, a set of mortar & pestle, a dialysis bag (10cm), 2 threads,
a glass rod, water-bath, a set of pipette (5ml) and a pipette-bulb, a plastic
cuvette and spectrophotometer UV/Vis.
Materials:
The materials required were emulsifying
wax, white soft paraffin, liquid paraffin, acetylsalicylic acid and distilled
water.
Procedure:
1.
50g
of Emulsifying Ointment is prepared by using the formula following:
Emulsifying
Ointment
|
Group
|
Material (g)
|
Total (g)
|
||
Emulsifying
Wax
|
White Soft
Paraffin
|
Liquid
Paraffin
|
|||
I
|
1,5
|
21
|
25
|
4
|
50
|
II
|
2,6
|
17
|
25
|
8
|
50
|
III
|
3,7
|
13
|
25
|
12
|
50
|
IV
|
4,8
|
9
|
25
|
16
|
50
|
2.
5g
of ointment formed is weighed. The ointment is put in the weighing boat and
labeled. The texture, clarity and the colour of the ointment formed are
discussed and compared.
3.
1.5g
of Acetylsalicylic acid is weighed and grinded with mortar and pestle.
4.
The
weighed amount of acetylsalicylic acid is mixed with 30g of ointment weighed by
using levigation method.
5.
7g
of Acetylsalicylic acid ointment is weighed and filled into the dialysis beg.
Both end of the beg are tied properly as shown as below.
6.
The
dialysis beg is put into a 100mL beaker with 50mL of distilled water which is
been heated on 370C.
7.
With
the interval of each 5 minutes, 3-4mL of the distilled water is pipetted out.
The release of acetylsalicylic acid from the ointment is determined by using
UV-visible spectrometer. Distilled water is stirred before the taking the
sample.
Result and Discussion:
1.Compare
physical characteristic of ointment that is formed and give your reasons.
Emulsifying wax is a waxy solid prepared from the Cetostearyl Alcohol
that contain Polyoxyethylene derivative of a fatty acid ester of Sorbitan. This
emulsifying wax is function to binds the water and oil in a cream or lotion
together permanently. If the emulsifying wax present the ingredients that made
from mixture of oil and water will be separate into oil and water-based and it
is needed to shake for mixing before used. Amount of emulsifying wax that are
used in ointment IV is less compared to the emulsifying I, II and III. So that
is why emulsifying ointment IV is easily to spread compared to emulsifying I,
II and III. Less amount of the emulsifying wax that is used in the ointment IV
make the ointment become very soft and it is easily to be applied to our skin.
Besides, liquid paraffin has a variety of uses and it is a mixture of
hydrocarbons that obtained through the petroleum distillation process. This
liquid paraffin is clear, oily, transparent and also colorless liquid. It does
not dissolve in the water, glycerol or cold ethanol, so that is why emulsifying
ointment IV is very greasy compared to the ointment I, II and also III which
contain less amount of liquid paraffin. Liquid paraffin also is low water
absorbing and has characteristic of greasiness which make the ointment become
very greasy if present more liquid paraffin in it. Clarity of the ointment for
all emulsifying ointment is not clear because presence of the liquid paraffin
which is oily. All emulsifying ointment are white in color because liquid
paraffin have characteristic of colorless liquid and clear.
- Plot the graph of UV
absorption against time. Give explanation.
In
this experiment, the dialysis bag is being used to indicate the human skin
where the drug is absorbed into the circulation or plasma, which is indicated
by the distilled water at 37 degree Celsius. UV absorption in this experiment
is used to measure the concentration of drug (acetylsalicylic acid) in the
distilled water versus time.
From the graph,
the UV absorption value increases with the time. This shows that the
concentration of drugs in distilled water increases with time. This is true as
the drug can diffuse into the distilled water throughout the period of
immersing in the water. The gradient of the graph indicates the rate of release
of the acetylsalicylic acid from the dialysis tube. Theoretically, the gradient
will become less steep as the time passes. This is because as the time passes,
the concentration of acetylsalicylic acid increases in the distilled water.
Initially, the distilled water in the surrounding is very hypotonic to the
content of in the dialysis, hence, the acetylsalicylic acid is very prone to
diffuse out to the hypotonic solution. When the time passes, the isotonicity
and the equilibrium of diffusion are more approached by the system, leading to
the less steep gradient which indicates the slower release rate of
acetylsalicylic acid. However, the graph of this experiment does not show such
pattern. This may be due to some experimental errors occurring throughout the
experiment.
The errors
include the non-uniformity of stirring of distilled water in the beaker,
leading the inaccurate result. Besides, errors may arise if the tube is not
tied tightly or there is leakage on the membrane. Also, the temperature is not
kept consistent enough. In addition, the wrong technique of using
spectrophotometry device also causes the inaccurate results. The smooth surface
of the cuvet should not face the source of UV light and the smooth surface
should be cleaned before placing it into device.
At the time t=0,
there might be little reading because some ointment acetylsalicylic acid is
adhered to the outer membrane during preparation of dialysis bag.
3. Graph of UV absorption against time is plotted for ointment formulation
which contains different composition. Compare and discuss the results
Based on the graph above, the average UV absorption for each formulation
increases with time owing to the increase in the concentration of
acetylsalicylic acid in the beaker. In every interval of 5 minutes, 3ml of
aliquot were taken from the solution surrounding the dialysis bag in the beaker
rendering a progressive decrease in amount of solution in the beaker. The
active ingredient in the ointment was being released into the solution in the
beaker from time to time. Thus, the concentration of the active ingredient-
acetylsalicylic acid increases progressively which is indicated by an increase
in the average UV absorption.
The standard deviation for formulation Iis quite large. This may due to some errors
occurred throughout the experiment. The formulation III shows a more consistent value compared to
other formulations while the value of standard deviation for formulation II and IV is still acceptable.
Drug diffusion of emulsifying ointment is affected by the formulation of
emulsifying wax and liquid paraffin. Theoretically, drug diffusion of
emulsifying ointment I is the most followed by emulsifying ointment II, III and
the drug diffusion of emulsifying ointment IV is the least. The more the
emulsifying wax, the more the drug will be diffuse out. This is shown in the
graph above.
4. What is the function of each materials used
in preparation of the ointment? How can different the composition of
Emulsifying wax and Liquid Paraffin can influence the physical properties of
the ointment and the rate of diffusion of the drug from the ointment?
Emulsifying wax is
a type of cosmetic emulsifying ingredient used primarily in the
manufacturing of creams, lotions, and other beauty products. The emulsification
occurs when two substances oil and water — are successfully bound together,
creating a sort of glue that combines the ingredients of a product.
The wax is sometimes labelled as emulsifying wax NF, which
means it meets the standards of a National Formulary, which is a medical manual
containing approved medicines in a particular country — the US, Britain and
Australia are a few countries that have national formularies. When included in
a recipe, emulsifying wax thickens the liquid and marries the
oil- and water-based elements of the creation. The wax itself is made
of either petroleum or vegetable wax that has been enhanced with a
chemical detergent. It is white in color, solid, and possesses a light alcohol
scent. The commonly prescribed amount of emulsifying wax NF is
three to six percent of the total weight of the recipe.
However,
liquid paraffin is a type of hydrocarbon base and is used to reduce the
viscosity of ointment or soften the ointment while white soft paraffin is used
as an emollient base in the ointment formulation.
In this practical, different amount of emulsifying
wax and liquid paraffin is used to prepare 50g of ointment. Since the
emulsifying wax is used to combine the water, oil and other ingredients
together in the ointment, the higher the concentration of the emulsifying wax,
the harder of the ointment produced. For liquid paraffin, its function is to
reduce the viscosity of ointment, thus the higher the concentration of the
liquid paraffin, the lower the viscosity of the ointment which meant that the
ointment is greasier. Hence, the ointment that increased in the concentration
of emulsifying wax and reduced in the amount of liquid paraffin will be harder
and less greasy compare to the ointment that prepared with the formulation that
decreased in the concentration of emulsifying wax and increased in the amount
of liquid paraffin.
When the concentration of emulsifying wax is
increased, the diffusion of the drug will decrease because emulsifying wax will
retard the drug release from the ointment and hence the diffusion of
acetylsalicylic acid from ointment cannot occur perfectly. However, an optimum
concentration of liquid paraffin in ointment will increase the diffusion rate
of acetylsalicylic acid from the dialysis tube because acetylsalicylic acid
which is hydrophilic tends to diffuse into the surrounding distilled water. The
diffusion rate of acetylsalicylic acid will decrease when the concentration of
liquid paraffin is beyond the optimum value. Thus, an optimum ratio of the
phases is needed to produce an ointment with good physical property and also
the drug releasing rate.
Conclusion:
As a conclusion, the assessment here showed that the
ointment composition will affect the physical property and the drug release
rate from the ointment.
References:
1.
Pharmaceutics:
the science of dosage form design,Aulton, M.E.2002
4.
Jelvehgari,
Mitra, Montazam, Hassan. 2011. Evaluation of mechanical and rheological
properties of metronidazole gel as local delivery system. Archives of Pharmacal
Research. 0253-6269
5.
H. C. Ansel, N. G. Popovich and L. V. Allen, Jr.
2005. Pharmaceutical Dosage Forms and
DrugDelivery Systems, 8th ed., Williams and Wilkins, Baltimore
It is very difficult to insert the ointment into the dialysis test...I think we should have the proper alternative way to insert it. Otherwise, the accuracy will be affected
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